1. Field of the Invention
The present invention relates to hand-guided sweeping machines, and, particularly, to sweeping machines of the type employing a rotary-driven cylindrical brush to propel debris into a detachable hopper, a blower (fan) for drawing a suction airstream through the machine to facilitate pickup of dust, and a filter disposed to remove dust from the airstream prior to passing through the blower.
2. Description of the Prior Art
In general, hand-guided sweeping machines including a removable hopper disposed to receive debris propelled by a rotary-driven cylindrical brush and a fan for drawing a suction airstream through the hopper are known. An example of such a prior art sweeper is described in U.S. Pat. No. 2,972,159 issued Feb. 21, 1961, to A. S. Swanson, et al.
It is also known to interpose a filter in the suction air stream with the filter disposed above the hopper so that in such sweepers, particles collected by the filter fall be shaken down into the hopper. An example of such a prior art sweeper is described in U.S. Pat. No. 3,189,931, issued on June 22, 1965, to R. C. Peabody. That sweeper employes an integral filter-hopper unit having stub pivots on its side. The stub pivots are releasably pivotally engaged by hydrolically driven arms on the sweeper frame. When the arms are in a lowered position, the hopper is disposed to receive particles propelled by cylindrical brushes. When the hopper is to be emptied, the hydraulic arms are raised, once the hopper-filter unit pivots under its own weight to dump its contents.
Another example of such a prior art sweeper is described in U.S. Pat. No. 4,580,313, issued on Apr. 8, 1986, to M. L. Blehert. That sweeper employs a box-shaped filter housing disposed immediately above the hopper. The rear upper end of filter housing is hinged to the frame of the sweeper in proximity to the blower inlet and the housing lowered to bring the inlet of the housing into communication with an opening in the top of the hopper. The hopper includes arms which are pivotally mounted to the sweeper frame. The filter housing is pivoted upward into a raised position to permit the hopper to be tipped for emptying or removal from the sweeper.
It is often necessary to empty the hopper at a site that is not accessible to a sweeper, requiring that the hopper be detached from the sweeper. In order to remove the hopper from the prior art devices the hopper must be lifted a significant distance to clear the coupling mechanism. Accordingly, in devices such as described in U.S. Pat. No. 4,580,313, the filter housing must be tilted and raised sufficiently to provide the necessary clearance for lifting the hopper from the machine frame. Further, since the hopper is pivotally mounted to the sweepers in the prior art and is often balanced for pivoting, there is a significant risk that the hopper will inadvertently be tipped prematurely, dumping its contents during the removal procedure. Such inadvertant spillage assumes additional significance since the filter housing is either unitary with the hopper, or is tilted and raised to provide clearance for the hopper. The filter is effectively removed from the blower intake, reducing the blow susceptible to dust and particles raised during the removal process.